Dentistry relies on light curing resins as sealants, adhesives, and as filler material for filling dental cavities. Light curing material is cured by exposure to radiant energy in spectral range tailored to the composition of the material. A light-curing unit containing a reflector lamp is used to irradiate the light curing material by directing light from the reflector lamp through a light guide positioned with its distal end adjacent to the light curing material to be cured. The light guide functions to channel the light to the material at the site of the dental restoration.
The physics of the transmission of light through a light conductor is well known. Practical factors and physical limitations of both doctor and patient often dictate the design of the light guides and light-curing units used in modern dentistry. The need for accessibility and maneuverability within the oral cavity of a patient requires the light guide to have a curved end section. Aside from these practical considerations attention must also be given to maximizing the transmission of light from the light source.
Conventional light guides typically comprise a solid conductor of either glass or plastic, or is composed of a fiber optic conductor consisting of multiple strands of glass fiber held together as a flexible bundle or fused into a solid rod of individual fibers. Conventional light guides are not as efficient as the instantly disclosed light guide as they typically produce high angle light that results in loss of light energy due to multiple reflections and the escape of light from the apparatus.
Light sources used for the purpose of photo-initiation of light curing resins and dental tooth whitening fall into two major categories. Light sources such as tungsten halogen, metal halide, and xenon all produce white light that is filtered to transmit only visible light within the general spectral range of 380-520 nanometers. Light sources such as laser and light emitting diode produce visible light which is closely matched to the photo-initiators used in light curing resins and activators found in dental tooth whitening formulations.
Light sources such as tungsten halogen, metal halide, and xenon are not very efficient at producing light energy within the spectral range useful for dental photo-polymerization and tooth whitening. The energy produced by these light sources in the form of ultraviolet and infrared is not used in the dental application. Light sources such as laser and LED that produce visible blue light with spectral output closely matching the photo-initiators used in dental resins and the activators found in dental tooth whitening formulations are much more efficient and produce less heat in the form of infrared wavelengths. Light emitting diodes last for thousands of hours with no degradation in light output eliminating the need to change lamps.
Prior use of Light Emitting Diodes for dental light sources relied on multiple LED's placed in arrays to generate enough power to be practical for dental curing. This is expensive and also increases the size of the device. Recent advancements in LED semiconductor technology have resulted in the introduction of a single blue LED that emits radiometric power levels sufficient to allow the rapid photo-polymerization of light curing resins and for use in dental tooth whitening. It is recognized that continued advancements in LED semiconductor technology will result in the use of different semiconductor substrate materials to alter the color spectra as well as increase radiometric power for single LED devices.
The domed lens cover used as part of the construction of these mass-produced LED's is designed so that light is visible from 360 degrees around the device. This is because the typical application for these devices are indicator lights such as traffic signal lights, automotive brake and signal lights, and signage. The present invention redirects the light energy emitted from the LED and focuses it toward the distal end of the invention in an efficient manner resulting in higher energy levels than possible with a traditional external reflector.